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-rw-r--r--libdimension/polynomial.c7
-rw-r--r--tests/libdimension/Makefile.am4
-rw-r--r--tests/libdimension/polynomial.c59
3 files changed, 66 insertions, 4 deletions
diff --git a/libdimension/polynomial.c b/libdimension/polynomial.c
index f361d38..32dd922 100644
--- a/libdimension/polynomial.c
+++ b/libdimension/polynomial.c
@@ -80,7 +80,7 @@ dmnsn_real_degree(double poly[], size_t degree)
static inline double
dmnsn_improve_root(double poly[], size_t degree, double x)
{
- double error;
+ double dx;
do {
/* Calculate the value of the polynomial and its derivative at once */
double p = poly[degree], dp = 0.0;
@@ -89,10 +89,9 @@ dmnsn_improve_root(double poly[], size_t degree, double x)
p = p*x + poly[i];
}
- double dx = p/dp;
- error = fabs(dx/x);
+ dx = p/dp;
x -= dx;
- } while (error > dmnsn_epsilon);
+ } while (fabs(dx) > dmnsn_epsilon);
return x;
}
diff --git a/tests/libdimension/Makefile.am b/tests/libdimension/Makefile.am
index f6918dc..252deba 100644
--- a/tests/libdimension/Makefile.am
+++ b/tests/libdimension/Makefile.am
@@ -22,6 +22,7 @@ INCLUDES = -I$(top_srcdir)/libdimension
check_LTLIBRARIES = libdimension-tests.la
check_PROGRAMS = error-test \
warning-test \
+ polynomial-test \
prtree-test \
png-test \
gl-test \
@@ -54,6 +55,9 @@ error_test_LDADD = libdimension-tests.la
warning_test_SOURCES = warning.c
warning_test_LDADD = libdimension-tests.la
+polynomial_test_SOURCES = polynomial.c
+polynomial_test_LDADD = libdimension-tests.la
+
prtree_test_SOURCES = prtree.c
prtree_test_LDADD = libdimension-tests.la
diff --git a/tests/libdimension/polynomial.c b/tests/libdimension/polynomial.c
new file mode 100644
index 0000000..230a1a7
--- /dev/null
+++ b/tests/libdimension/polynomial.c
@@ -0,0 +1,59 @@
+/*************************************************************************
+ * Copyright (C) 2010 Tavian Barnes <tavianator@gmail.com> *
+ * *
+ * This file is part of The Dimension Test Suite. *
+ * *
+ * The Dimension Test Suite is free software; you can redistribute it *
+ * and/or modify it under the terms of the GNU General Public License as *
+ * published by the Free Software Foundation; either version 3 of the *
+ * License, or (at your option) any later version. *
+ * *
+ * The Dimension Test Suite is distributed in the hope that it will be *
+ * useful, but WITHOUT ANY WARRANTY; without even the implied warranty *
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
+ * General Public License for more details. *
+ * *
+ * You should have received a copy of the GNU General Public License *
+ * along with this program. If not, see <http://www.gnu.org/licenses/>. *
+ *************************************************************************/
+
+/*
+ * Basic tests of PR-trees
+ */
+
+#include "dimension.h"
+#include <stddef.h>
+#include <stdio.h>
+
+int
+main()
+{
+ double poly[6], x[5];
+ // poly[] = (x + 1)*(x - 1.2345)*(x - 2.3456)*(x - 5)*(x - 100)
+ poly[5] = 1.0;
+ poly[4] = -107.5801;
+ poly[3] = 770.2260432;
+ poly[2] = -1215.2863928;
+ poly[1] = -646.270936;
+ poly[0] = 1447.8216;
+
+ size_t n = dmnsn_solve_polynomial(poly, 5, x);
+ if (n != 4) {
+ fprintf(stderr,
+ "--- Wrong number of roots found (%zu, should be %u) ---\n",
+ n, 4);
+ return EXIT_FAILURE;
+ }
+
+ for (size_t i = 0; i < n; ++i) {
+ double evmin = dmnsn_evaluate_polynomial(poly, 5, x[i] - dmnsn_epsilon);
+ double ev = dmnsn_evaluate_polynomial(poly, 5, x[i]);
+ double evmax = dmnsn_evaluate_polynomial(poly, 5, x[i] + dmnsn_epsilon);
+ if (fabs(evmin) < ev || fabs(evmax) < ev) {
+ fprintf(stderr, "--- Root %.15g is inaccurate! ---\n", x[i]);
+ return EXIT_FAILURE;
+ }
+ }
+
+ return EXIT_SUCCESS;
+}